| Popis: |
Selective cementing is required in challenging wellbores with tight mud-weight windows between low-and high-pressure formations around the Arabian Gulf. It is typical to cover the Thamama 5,6 high-pressure formation and the Mishrif low-pressure formation in the Satah Al Razboot (SARB) field and the Salabikh formation in the Zakum and Umm Shaif fields in a single 12.25-in. hole section. This paper will discuss the reliability and cost impact of using new packoff stage-cementing equipment for cementing and zonal isolation in this situation. Operators have a history of compromised casing integrity requiring intervention of wells because of the short lifetime of stage-cementing equipment. They have been forced to select other, more costly and more time-consuming methods (requiring four to six trips), such as installing a liner hanger and a tieback to surface. Although these methods are reliable and field proven, they have added considerable upfront investment in rig days and greater expense to the operation. The evolution of reliable, gas-tight stage cementers (two-trip systems) rated at up to 10,000 psi at 350°F reduces the required number of operating days and total well costs and expands the technology limit for more challenging well conditions. Rigorous testing and equipment qualification to International Organization for Standardization (ISO) 14998 V0 and ISO 14310 V0 have established confidence in stage-cementing tools with integral packer and slip systems. Based on this validation, wells in the Arabian Gulf Region can now be constructed using a single long string of casing, thereby eliminating the added expense of a liner hanger and liner tieback system. In addition to equipment savings, these stage-cementing tools reduce by as many as to 6 to 7 days the total number of operating days required to construct the well. The tools also reduce approximately US $1 to $1.5 million in direct cost and subsequent costs of intervention over the life of the asset. This paper will provide insight into equipment installation methods and comparative time and cost for the use of pack-off, two-stage cementing tools in the United Arab Emirates. Technology innovation was achieved by combining completion accessories and downhole products that meet international standards set forth by ISO/API. This maximizes the reliability and validates the extended limitations of the technology to apply alternative well construction techniques that will retain wellbore integrity and reduce cost over the life of the well. |
